In recent years, there have been developed techniques to display an image, picked up by a camera mounted in a vehicle, on a monitor installed in proximity to the driver's seat. With these techniques, drivers can recognize any obstacle or the like present at the drivers' blind spot. However, it is difficult to display an image easily viewable to drivers because of the characteristics of a camera or the position of installation of a camera. For this reason, drivers used to often feel discomfort.
As a technique to solve this problem, for example, a vehicle surroundings monitoring device is disclosed in Patent Document 1. This vehicle surroundings monitoring device makes an image picked up by a camera easily viewable to a driver by taking the following measure: when the image is displayed, an upper mask positioned at the upper part of a screen and a lower mask positioned at the lower part of the screen are combined with the image. The upper mask cited here is a mask composed of an upper side mask area that is disposed along the upper side of the screen and convex downward and a central mask area extended upward from the central part of the screen. The lower mask is a mask formed in the shape of an arc gently convex upward along the lower side of the screen.
With the vehicle surroundings monitoring device disclosed in Patent Document 1, as a result, an image can be displayed so that it is narrower as it goes to the central area in the horizontal direction and is wider as it goes to either end. That is, a panoramic image can be displayed.    Patent Document 1: JP-A-2006-262447 (corresponding to US2006/0187238)
On the other hand, images displayed by the vehicle surroundings monitoring device disclosed in Patent Document 1 involves a drawback that the information of the central area in the horizontal direction is reduced. Therefore, it is difficult to apply the invention disclosed in Patent Document 1 to images in which the information of the central area in the horizontal direction is especially important to a driver (for example, rear view images used when a vehicle is reversed).